Image processing apparatus

ABSTRACT

An image processing apparatus includes an image pickup circuit having a plurality of photographic modes, such as television standards, a compression processing circuit for performing compression processing of an image pickup signal outputted from the image pickup circuit, the compression circuit having a plurality of compression modes, and a selecting circuit for selecting one of the compression modes of the compression processing circuit in accordance with a selected one of the photographic modes of the image pickup circuit.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an image processing apparatusincluding an image pickup system and compression processing means forcompressing a photographic image obtained from the image pickup system.

[0003] 2. Description of the Related Art

[0004]FIG. 1 is a schematic block diagram showing the arrangement of aconventional example in which a video camera is integrated with adigital video tape recorder for digitally recording a video signal.

[0005] In the example shown in FIG. 1, an image pickup device 10 isprovided with a complementary color filter and performspseudo-interlaced reading of electric charge stored by field storage.Specifically, as shown in FIG. 2, the image pickup device 10 is providedwith a mosaic color filter made up of filter elements: white (W), cyan(Cy), yellow (Ye) and green (G). The image pickup device 10 outputs theadded values of two adjacent upper and lower lines, and a luminancesignal processing circuit 12 adds together the values of two adjacentpixels contained in the output of the image pickup device 10, therebyforming a luminance signal. A chrominance signal processing circuit 14obtains differences between the values of the two adjacent pixels,thereby forming color-difference signals.

[0006] More specifically, a luminance signal Yn obtained from a line #nand a luminance signal Yn+1 obtained from a line #(n+1) are as follows:

Yn=(W+Cy)+(G+Ye)

Yn+1=(W+Ye)+(G+Cy)

[0007] and the associated chrominance signals Cn and Cn+1 are asfollows:

Cn=(W+Cy)−(G+Ye)

Cn+1=(W+Ye)−(G+Cy)

[0008] If the characteristic of each filter element W is equal to thesum of R (red), G (green) and B (blue), i.e., R+G+B; the characteristicof each filter element Cy is equal to B+G; and the characteristic ofeach filter element Ye is equal to Ye=R+G, the following equations areobtained: Yn = Yn + 1 = 2R + 4G + 2B Cn = 2(B − G)Cn + 1 = 2(R − G)

[0009] As shown in FIG. 2, the line numbers of adjacent upper and lowerlines to be added together are made to differ between an even field andan odd field, whereby an interlaced signal is obtained. To perform thisaddition, the image pickup device 10 needs to be provided with aphotoelectric conversion element having lines the number of which isequivalent to the number of lines per frame (in the NTSC system, 525lines). In the case of the NTSC system, in a line Lm of the image pickupdevice 10 shown in FIG. 1, m is 525.

[0010] A luminance signal Y formed by the luminance signal processingcircuit 12 and a chrominance signal C formed by the chrominance signalprocessing circuit 14 are stored in an image memory 16 under the controlof a memory control circuit 18. When image data for one frame are storedin the image memory 16, a motion detecting circuit 20 discriminatesbetween a moving image portion and a still image portion. An imagecompressing circuit 22 compresses the image data supplied from the imagememory 16, by using correlations present in the image. At this time, theimage compressing circuit 22 adaptively switches compression algorithmsbetween the still image portion and the moving image portion inaccordance with the detection result provided by the motion detectingcircuit 20.

[0011] The compressed image data is applied to an image recording device24, and the image recording device 24 records the compressed image dataon a recording medium.

[0012] A system control circuit 26 controls the entire arrangement inaccordance with the operation of a key operation device 28.

[0013] In the above-described arrangement, pseudo-interlaced fieldimages are compressed and recorded on the recording medium.

[0014] In the conventional example in which compression processing isperformed after field images are combined into a frame image, there isthe problem that if field images of a fast moving subject are combinedinto a frame image, the resultant image may be blurred as shown in FIGS.3(a) to 3(c). FIG. 3(a) shows an odd field image, FIG. 3(b) shows thesucceeding even field image, and FIG. 3(c) shows the frame imageobtained by combining the odd and even field images.

[0015] Compression of an image utilizes correlations which appear in theimage in the space and time-axis directions thereof. In general, a framepicture the vertical line-to-line distance of which is smaller than thatof a field picture contains higher correlations. For this reason, asdescribed above, the conventional example adopts the compression methodof adaptively switching compression algorithms between a still imageportion and a moving image portion in a frame image.

[0016] As a result, the conventional example necessarily needs a motiondetecting circuit for detecting a still image portion and a moving imageportion, and, in addition, a substantially high detection accuracy isneeded. This problem makes it difficult to reduce the size of thecircuit.

[0017] As is known to those skilled in the art, since a conventionalcamera-integrated type of VTR does not conform to a plurality oftelevision standards, a plurality of camera-integrated types of VTRsmust be prepared and selectively used according to individual purposes.With the diversification of broadcasting systems, it becomes far morenecessary to exchange program software tapes between different nationsor to produce software conforming to multiple broadcasting systems.However, if a plurality of broadcasting systems are to be handled, aplurality of existing VTRs are needed, so that practical inconvenienceswill be encountered. For this reason, it has been desired to provide aVTR unit capable of conforming to multiple broadcasting systems.

[0018] As is also known to those skilled in the art, systems forrecording and reproducing a digitized video signal are individuallydesigned according to necessary image qualities orrecordable/reproducible data rates. However, if system designs differ incoding sampling frequency which is a primary parameter for determiningimage quality, when one system is connected to another video system,various problems occur.

[0019] Such conventional systems which are separately designed accordingto individual required image qualities have the problem that it isimpossible to readily exchange image data between systems via media.

SUMMARY OF THE INVENTION

[0020] It is, therefore, an object of the present invention to providean image processing apparatus capable of solving the above-describedproblems.

[0021] To achieve the above object, in accordance with one aspect of thepresent invention, there is provided an image processing apparatus whichcomprises image pickup means having a plurality of photographic modes,compression processing means for performing compression processing of animage pickup signal outputted from the image pickup means, thecompression means having a plurality of compression modes, and selectingmeans for selecting one of the compression modes of the compressionprocessing means in accordance with a selected one of the photographicmodes of the image pickup means.

[0022] According to the above arrangement, it is possible to fullyutilize the performance of the compression processing means, so that itis possible to realize a good image quality and a high compressionratio.

[0023] Another object of the present invention is to provide a videorecording apparatus, a video reproducing apparatus and a video recordingand reproducing apparatus, such as a multimode-capable camera-integratedtype VTR capable of effecting camera photography, compression signalprocessing and video recording according to a plurality of televisionstandards.

[0024] To achieve the above object, in accordance with another aspect ofthe present invention, there is provided a video recording apparatuswhich comprises image pickup means capable of conforming to a pluralityof television standards, recording means for compressing data outputtedfrom the image pickup means at a compression ratio according to atelevision standard selected from the plurality of television standardsand recording on a recording medium compressed data and identificationinformation for identification of the selected television standard,setting means for setting the selected television standards, andcontrolling means for controlling the image pickup means and therecording means in accordance with a setting of the setting means.

[0025] To achieve the above object, in accordance with another aspect ofthe present invention, there is provided a video reproducing apparatuswhich comprises reproducing means for reproducing video data compressedaccording to a television standard and identification information foridentification of the television standard from a recording medium onwhich the video data and the identification information are recorded,and performing expansion processing of the video data, and controllingmeans for controlling the reproducing means on the basis of theidentification information reproduced from the recording medium.

[0026] To achieve the above object, in accordance with another aspect ofthe present invention, there is provided a video recording andreproducing apparatus which comprises a system converter for convertinga first video signal conforming to a first television standard into asecond video signal conforming to a second television standard,recording means for recording the first or second video signal on arecording medium, switching means for supplying to the recording meansthe first video signal or the second video signal obtained from thesystem converter, reproducing means for reproducing the first or secondvideo signal from the recording medium, and signal supplying means forsupplying the first video signal reproduced by the reproducing means tothe system converter.

[0027] According to the first two aspects of the present invention, witha single camera-integrated type VTR, it is possible to automaticallyperform recording processing and reproduction processing according to aplurality of compression modes which conform to a plurality oftelevision standards.

[0028] According to the third aspect of the present invention, thesystem converter is used during both recording and reproduction so thatit is possible to perform recording and reproduction of or provide amonitor output of a video signal according to a desired televisionstandard.

[0029] In accordance with another aspect of the present invention whichhas been made to solve the aforesaid problems, there is provided a videosystem which comprises recording means for recording video information,which is hierarchically coded, while forming a data recording area on arecording medium in accordance with a hierarchical structure of thevideo information and at least one recording mode of a plurality ofrecording modes each having a different recording processing, andreproducing means capable of setting a reproduction mode according tothe at least one recording mode and the hierarchical structure, orreproducing means capable of setting a reproduction mode within a rangeof the hierarchical structure irrespective of the at least one recordingmode.

[0030] According to the above aspect, it is possible to performreproduction processing for reproducing recorded data from aninformation recording medium which is recorded in one of the pluralityof recording modes, in an arbitrary reproduction mode in accordance withthe conditions of a reproduction side. The recorded data is reproducedfrom only a data recording area which corresponds to a necessaryinformation hierarchy within information hierarchically recorded on arecorded tape.

[0031] The above and other objects, features and advantages of thepresent invention will become apparent from the following detaileddescription of preferred embodiments of the present invention, taken inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0032]FIG. 1 is a schematic block diagram of the arrangement of aconventional camera-integrated type digital recording apparatus;

[0033]FIG. 2 is an explanatory view of the color-filter arrangement ofthe image pickup device shown in FIG. 1 and the manner of reading ofelectric charge therefrom;

[0034] FIGS. 3(a), 3(b) and 3(c) are explanatory views of an image bluroccurring in a frame image as the result of a combination of fieldimages;

[0035]FIG. 4 is a schematic block diagram of the arrangement of an imageprocessing apparatus according to one embodiment of the presentinvention;

[0036]FIG. 5 is an explanatory view of the color-filter arrangement ofthe image pickup device shown in FIG. 4 and the manner of reading ofelectric charge therefrom;

[0037]FIG. 6 is a schematic block diagram of the arrangement of acamera-integrated type video recording apparatus according to a secondembodiment of the present invention;

[0038]FIG. 7 is a schematic block diagram of one example of thebroadcasting system conversion circuit shown in FIG. 6;

[0039]FIG. 8 is an explanatory, schematic view of a side panel systemfor aspect-ratio conversion;

[0040]FIG. 9 is an explanatory, schematic view of a squeeze system foraspect-ratio conversion;

[0041]FIG. 10 is an explanatory, schematic view of a letter box systemfor aspect-ratio conversion;

[0042]FIG. 11 is a comparative table of operating modes;

[0043]FIG. 12 is a schematic block diagram of the arrangement of thevideo camera shown in FIG. 6;

[0044]FIG. 13 is a schematic block diagram of the arrangement of animage compressing circuit in the embodiment shown in FIG. 6;

[0045]FIG. 14 is an explanatory view of a block formed by the blockingcircuit shown in FIG. 13;

[0046]FIG. 15 is an explanatory view of the pixel arrangements of aneven field and an odd field;

[0047]FIG. 16 is an explanatory view of the output of the DCT circuitshown in FIG. 13;

[0048]FIG. 17 is an explanatory view of a zigzag scan;

[0049]FIG. 18 is a schematic block diagram of the arrangement of therecording system of a digital video tape recorder;

[0050]FIG. 19 is a schematic view of a recording track pattern on amagnetic tape;

[0051]FIG. 20 is a view of the data structure of a sub-code;

[0052]FIG. 21 is a schematic block diagram of the arrangement of thereproducing system of the digital video tape recorder;

[0053]FIG. 22 is a table of the recording characteristics of individualmodes;

[0054]FIG. 23 is a schematic view showing a head for use in an SD-Lowmode;

[0055]FIG. 24 is a schematic view showing tracks for one field in theSD-Low mode;

[0056]FIG. 25 is a chart showing the timing of head switching which isperformed in the SD-Low mode;

[0057]FIG. 26 is a schematic view showing a head for use in an SD-Highmode;

[0058]FIG. 27 is a schematic view showing tracks for one field in theSD-High mode;

[0059]FIG. 28 is a chart showing the timing of head switching which isperformed in the SD-High mode;

[0060]FIG. 29 is a schematic view showing a head for use in an HD mode;

[0061]FIG. 30 is a schematic view showing tracks for one field in the HDmode;

[0062]FIG. 31 is a chart showing the timing of head switching which isperformed in the HD mode;

[0063]FIG. 32 is a flowchart of mode identification during reproduction;

[0064]FIG. 33 is a block diagram showing one example of a broadcastingsystem converter which serves as an up converter;

[0065]FIG. 34 is a schematic block diagram showing a video recording andreproducing apparatus according to another embodiment of the presentinvention;

[0066]FIG. 35 is a flowchart of a mode setting process according toanother embodiment of the present invention;

[0067]FIG. 36 is an explanatory view of the principle of hill climbingfocus adjustment;

[0068]FIG. 37 is a view showing the relationships between TV forms andfrequency characteristics;

[0069]FIG. 38 is a schematic view of a hierarchical VTR recordingapparatus according to another embodiment of the present invention;

[0070]FIG. 39 is a conceptual view of the SD recording operation of thehierarchical VTR recording apparatus;

[0071]FIG. 40 is a conceptual view of the HD recording operation of thehierarchical VTR recording apparatus;

[0072]FIG. 41 is a schematic block diagram of a hierarchical VTRreproducing apparatus (HD) according to another embodiment of thepresent invention;

[0073]FIG. 42 is a conceptual view of the HD reproducing operation ofthe hierarchical VTR reproducing apparatus;

[0074]FIG. 43 is a conceptual view of SD reproduction from an HDrecorded medium to be performed by the hierarchical VTR reproducingapparatus;

[0075]FIG. 44 is a conceptual view showing the operation a hierarachicalVTR to perform SD reproduction of an SD recording;

[0076]FIG. 45 is a track view showing the SD reproduction of an HDrecording by the hierarchical VTR;

[0077]FIG. 46 is a view showing two kinds of trace angles for HD and SDin the hierarchical VTR;

[0078]FIG. 47 is a list of the reproducing modes of a hierarchical VTRfor SD signals;

[0079]FIG. 48 is a list of the reproducing modes of a hierarchical VTRfor HD signals; and

[0080]FIG. 49 is a schematic view showing a hierarchical VTR reproducingapparatus (SD).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0081] The present embodiments are based on the arrangement in which thepresent invention is applied to an image processing apparatus capable ofcoping with a plurality of photographic modes or television standards,as well as of performing recording and reproduction processings onhierarchically coded video signals.

[0082] Each of the embodiments of the present invention will bedescribed below with reference to the accompanying drawings.

[0083]FIG. 4 is a schematic block diagram showing the arrangement of animage processing apparatus according to one embodiment of the presentinvention. An image pickup device 30 is capable of selectivelyperforming a field reading operation and a frame reading operation, andthe color-filter arrangement of the image pickup device 30 is identicalto that of the image pickup device 10 shown in FIG. 1. Although theimage pickup device 10 is arranged to output the results of additions ofthe respective pairs of adjacent lines, the image pickup device 30 ofthis embodiment is capable of independently outputting a charge signalfrom each pair of adjacent lines, as shown in FIG. 5. The field readingoperation and the frame reading operation of the image pickup device 30primarily differ in reading frequency, and switching between the fieldreading operation and the frame reading operation is performed by ascanning switching circuit 32.

[0084] An even line processing circuit 34 computes charge signals readfrom the even lines of the image pickup device 30, with respect to allthe adjacent pixels, thereby forming a luminance signal Ye of an evenfield. An odd line processing circuit 36 computes charge signals readfrom the odd lines of the image pickup device 30, with respect to allthe adjacent pixels, thereby forming a luminance signal Yo of an oddfield. Also, a chrominance signal processing circuit 38 performsaddition of the charge signals read from the even and odd lines of theimage pickup device 30, with respect to all the adjacent lines, as wellas subtraction of the same charge signals with respect to all theadjacent pixels, thereby a chrominance signal C.

[0085] Specifically, a luminance signal Yn obtained from a line #n ofthe odd field and a luminance signal Yn+1 obtained from a line #(n+1)are as follows:

Yn=W+G

Yn+1=Cy+Ye

[0086] and the associated chrominance signals Cn and Cn+1 are asfollows:

Cn=(W+Cy)−(G+Ye)

Cn+1=(W+Ye)−(G+Cy)

[0087] If the characteristic of each filter element W is equal to thesum of R (red), G (green) and B (blue), i.e., R+G+B; the characteristicof each filter element Cy is equal to B+G; and the characteristic ofeach filter element Ye is equal to Ye=R+G, the following equations areobtained: Yn = Yn + 1 = R + 2G + B Cn = 2(B − G) Cn + 1 = 2(R − G)

[0088] Regarding the even field as well, luminance signals andchrominance signals can be obtained through similar computations.

[0089] Photoelectrically converted signals, which have been obtainedfrom lines L1 to Lm (m=525 in the NTSC system) corresponding tohorizontal scanning lines which constitute a television picture, areapplied to the even line processing circuit 34, the odd line processingcircuit 36 and the chrominance signal processing circuit 38, and theluminance signal Ye and the luminance signal Yo as well as thechrominance signal C which is common to the signals Ye and Yo areformed.

[0090] A frame photographic image outputted from the image pickup device30 is stored in an image memory 42 in the following manner. The imagepickup device 30 outputs the photoelectrically converted signals of allthe lines in the order of the lines, or simultaneously outputs therespective photoelectrically converted signals of the even lines and theodd lines in line order. Since a switch 44 is open, the luminance signalYe formed by the even line processing circuit 34 passes through an adder40 without being subject to addition, and is applied to the image memory42. The luminance signal Yo formed by the odd line processing circuit 36and the chrominance signal C formed by the chrominance signal processingcircuit 38 are also applied to the image memory 42. The image memory 42stores the luminance signals Ye and Yo and the chrominance signal Cunder the control of a memory control circuit 46. Thus, a frame imageobtained by one exposure cycle is stored in the image memory 42. Theabove-described operation is hereinafter referred to as the “frame imagepickup mode”.

[0091] The operation of combining field photographic images obtained bythe image pickup device 30 to form a frame image and storing theresultant frame image in the image memory 42 is performed in thefollowing manner. The image pickup device 30 outputs thephotoelectrically converted signals of all the lines in the order of thelines, or simultaneously outputs the respective photoelectricallyconverted signals of the even lines and the odd lines in line order. Inthis reading stage, image data for an odd field is first stored in theimage memory 42. Specifically, the image memory 42 stores the luminancesignal Yo of the odd field which is formed by the odd line processingcircuit 36 as well as the chrominance signal C formed by the chrominancesignal processing circuit 38.

[0092] During the next field, the switch 44 is closed and the imagememory 42 is made to operate in a read modify write mode, therebyfeeding the stored luminance signal Yo back to the adder 40 through theswitch 44. Similarly to the aforesaid odd field, the image pickup device30 outputs the photoelectrically converted signals of all the lines inthe order of the lines, or simultaneously outputs the respectivephotoelectrically converted signals of the even lines and the odd linesin line order. In this reading stage, the even line processing circuit34 and the chrominance signal processing circuit 38 operate, and theadder 40 adds the luminance signal Yo fed back from the image memory 42to the luminance signal Ye formed by the even line processing circuit34. Thus, it is possible to obtain a result similar to the result oftwo-line addition described previously in connection with theconventional example. The image memory 42 sequentially stores the outputof the adder 40 and the output of the chrominance signal processingcircuit 38 into predetermined memory locations. Thus, a frame image inwhich the field images obtained through two exposure cycles are combinedis stored in the image memory 42. The above-described operation isreferred to as the “field image pickup mode”.

[0093] When the image data for one frame is stored in the image memory42, the image compressing circuit 48 compresses the image data stored inthe image memory 42 in a compression mode according to a control signalsupplied from a system control circuit 52. For example, according towhich of the frame image pickup mode and the field image pickup mode isactive, a block to be formed by block coding such as DCT (discretecosine transform), which block is a main unit in image compressionprocessing, is determined as a field-based block or a frame-based block.

[0094] The compressed image data outputted from the image compressingcircuit 48 is applied to an image recording device 50, and the imagerecording device 50 records the compressed image data on a recordingmedium.

[0095] The system control circuit 52 controls the entire apparatus inaccordance with the operation of a key operation device 54.

[0096] As a matter of course, it is also possible to select acompression system from among various compression coding systems otherthan DCT. For example, if a DPCM system which is one kind of predictivecoding system is employed, in the case of the field image pickup mode inwhich a higher correlation appears in a horizontal direction than in avertical direction, compression is performed by a horizontal DPCM systemof performing a differential computation in the horizontal direction,while, in the case of the frame image pickup mode in which a highercorrelation appears in a vertical direction than in a horizontaldirection, compression is performed by a vertical DPCM system ofperforming a differential computation in the vertical direction.

[0097] In the above-described embodiment, switching between field-basedimage compression and block-based image compression is performedaccording to which of the field image pickup mode and the frame imagepickup mode has been selected. However, as a matter of course, it isalso possible to adopt an arrangement capable of selecting the fieldimage pickup mode or the frame image pickup mode in accordance withwhether the field-based image compression or the frame-based imagecompression has been selected. In other words, it is possible to reducea degradation of image quality by linking the field image pickup mode orthe frame image pickup mode with the field-based image compression orthe frame-based image compression.

[0098] Another embodiment of the present invention will be describedbelow in which the present invention is applied to a camera-integratedtype video recording apparatus which is compatible to an existingbroadcasting system (for example, the NTSC system (SD)) and ahigh-definition television system (for example, a “high-vision” system(HD)) and of performing camera photography, compression processing andrecording which is intended to two layers of image structures (SD andHD) each having a different image-quality design. FIG. 6 is a schematicblock diagram of the arrangement of the entire apparatus.

[0099] Referring to FIG. 6, an HDTV camera 60 is arranged to output ahigh-definition television signal, i.e., an HD signal. According to atelevision studio standard, the number of effective pixels per picked-upimage is 1,920 pixels in the horizontal direction and 1,035 pixels inthe vertical direction, and the sampling frequency is 75.3 MHz. Theoutput of the camera 60 enters two different paths. The signal which hasentered one path is applied to an image pickup mode selecting circuit 64via a broadcasting system conversion circuit 62, while the signal whichhas entered the other paths is directly applied to the image pickup modeselecting circuit 64.

[0100] The broadcasting system conversion circuit 62 is a down converterfor converting an HD signal into a signal conforming to any of the NTSC,PAL and SECAM systems which are standard broadcasting systems(hereinafter referred to as the “SD system”).

[0101] One example of the broadcasting system conversion circuit 62 forconverting an HD signal into an NTSC signal is shown in FIG. 7. Sincethe HD signal has an aspect ratio of 16:9 and the SD signal has anaspect ratio of 4:3, an aspect ratio conversion circuit 100 converts the16:9 aspect ratio into the 4:3 aspect ratio.

[0102] Specifically, it is possible to select a desired system fromamong a side panel system in which the right and left end portions of ahigh-vision image are omitted (refer to FIG. 8), a squeeze system (or afull-display system) in which a high-vision image is compressed in thehorizontal direction (refer to FIG. 9), and a letter box system in whichan image of 16:9 aspect ratio is displayed in a picture of 4:3 aspectratio (refer to FIG. 10). In the case of the letter box system, althoughempty spaces are formed in the top and bottom portions of a picture,they are displayed in black. If the HD signal is to be converted intothe NTSC system, the side panel system or the squeeze system issuitable, while the letter box system is suited to a case where it isdesired to fully utilize the photographic field angle of the HD camera60.

[0103] The HD signal and the SD signal greatly differ in the number ofhorizontal scanning lines. A number-of-scanning-lines conversion circuit102 converts the number of horizontal scanning lines of the HD output ofthe aspect ratio conversion circuit 100 into the number of horizontalscanning lines conforming to the SD system. For example, signals for therequired horizontal scanning lines are formed by a verticalinterpolation filter.

[0104] A field frequency conversion circuit 104 converts the fieldfrequency of the output of the number-of-scanning-lines conversioncircuit 102 (60 HZ in the case of the high-definition signal) into afield frequency conforming to the SD system (59.94 Hz in the case of theNTSC system). This frequency conversion can be executed at real time bya time-base corrector having a function similar to a frame synchronizer.

[0105] In a generally used frame synchronizer, in the case of a capacityof one frame memory, one frame cap occurs at intervals of approximately33 seconds and causes an unnatural discontinuity in a moving image. Incontrast, motion-adaptive type field frequency conversion detectsmotions and scene changes by using a frame difference signal, andperforms frame skipping if the following four conditions are satisfied:

[0106] 1) an image signal indicates a still image;

[0107] 2) a scene change has occurred;

[0108] 3) a moving-image area is comparatively small; and

[0109] 4) a frame buffer memory is full.

[0110] An NTSC encoder 106 converts the output of the field frequencyconversion circuit 104 into a television signal conforming to the NTSCsystem.

[0111] In the present embodiment, in the case of the SD system as well,it is possible to select a high image quality mode for business use(horizontal resolution: approximately 450 lines) and a standard imagequality mode for home use (horizontal resolution: approximately 230lines). The former mode is hereinafter referred to as the “SD-Highmode”, while the latter mode is hereinafter referred to as the “SD-Lowmode”. A mode for recording the HD signal is hereinafter referred to asthe “HD mode”. An operator can selectively set the HD mode, the SD-Highmode or the SD-Low mode by means of an operation panel 92, and a systemcontrol circuit 90 controls the image pickup mode selecting circuit 64in accordance with the mode set by the operator. The image pickup modeselecting circuit 64 selects the HD signal output of the camera 60 inthe case of the HD mode or the output of the broadcasting systemconversion circuit 62 in the case of the SD-High mode or the SD-Lowmode.

[0112] The signal selected by the image pickup mode selecting circuit 64is applied to a compression circuit 66. The compression circuit 66 isprovided with a plurality of compression modes (in the shown example, amode #1 and a mode #2) so that a compression ratio and a compressioncoding system can be individually selected. The compression ratio isselected from among, for example, 1/4, 1/8, 1/16 and 1/32. Thecompression coding system is selected from, for example, DCT, DPCM,Hadamard transform and ADRC. In the arrangement shown in FIG. 6, forexample, DCT and DPCM may be allocated to the compression mode #1 andthe compression mode #2, respectively, or the compression ratio may bevaried under a single compression coding system.

[0113] The compression circuit 66 compresses the output of the imagepickup mode selecting circuit 64 in the compression mode #1 as well asin the compression mode #2. The data compressed in the compression mode#1 and the compression mode #2 are both applied to a compression modeselecting circuit 68. The compression mode selecting circuit 68 selectseither one of the data compressed in the compression mode #1 and thedata compressed in the compression mode #2, in accordance with a controlsignal supplied from the system control circuit 90, and applies theselected compressed data to a recording processing circuit 70.

[0114] The modes to be selected by the image pickup mode selectingcircuit 64 and the compression mode selecting circuit 68 are closelyrelated to factors, such as a recording time or image quality to beselected for a recording system and the quality of an image to be pickedup by the camera 60 or a mode set for the camera 60. The modes areautomatically determined in association with such factors.

[0115] According to a relationship with a recording system which will bedescribed later, it is desirable that the data rates of imagescompressed in the respective compression modes have a relationshiprepresented by an integer ratio, for example, 50 Mbps in the HD mode, 25Mbps in the SD-High mode and 12.5 Mbps in the SD-Low mode, as shown inFIG. 22.

[0116] A recording processing circuit 70 applies recording processing,such as modulation, to the compressed data supplied from the compressionmode selecting circuit 68, divides the processed data into two channels,and outputs the divided data to the respective channels. Recordingamplifiers 72 a and 72 b amplify the respective outputs of the recordingprocessing circuit 70. A rotary drum 74 is provided with two pairs ofheads 76 a, 76 b and 78 a, 78 b. The outputs of the recording amplifiers72 a and 72 b are respectively recorded on a magnetic tape 80 by theheads 76 a, 76 b and 78 a, 78 b. The width of each track formed on themagnetic tape 80 is the same for any of the HD mode, the SD-High modeand the SD-Low mode.

[0117] A servo circuit 82 causes a drum motor 84 to rotate the rotarydrum 74 at a predetermined rotational speed, and also causes a capstanmotor 86 to rotate a capstan 88, thereby causing the magnetic tape 80 torun at a predetermined speed. The system control circuit 90 supplies tothe servo circuit 82 a target value based on an operation mode accordingto an operation instruction inputted through the operation panel 92.

[0118]FIG. 11 shows the relationships between the modes selected throughthe operation panel 92 and the image pickup systems, the compressionratios and the recording data rates.

[0119] The camera 60 shown in FIG. 6 will be described in detail withreference to FIG. 12. A photographic lens unit 110 includes a focusinglens 100 a for adjusting its focal length and a zooming lens 10 b forvarying its magnification, and focuses an optical image of a subject onthe photoelectric conversion face of an image pickup device 114 via aniris 112. A predetermined color filter 116 is attached to thephotoelectric conversion face of the image pickup device 114.

[0120] The image pickup device 114 operates in accordance with a clocksupplied from a clock generating circuit 118, and outputs a chargesignal. The output of the image pickup device 114 is noise-reduced by aCDS circuit 120 and is then gain-controlled by an AGC circuit 122. Theoutput of the AGC circuit 122 is applied to an exposure control circuit124, a focus control circuit 126, a white balance adjustment circuit 128and a color processing circuit 130.

[0121] A driving circuit 132 a and a motor 132 b drive the focusing lens110 a along the optical axis, a driving circuit 134 a and a motor 134 bdrive the zooming lens 110 b along the optical axis, and a drivingcircuit 136 a and a motor 136 b drive the iris 112 to cause it to openand close.

[0122] A system control circuit 138 controls the gain of the AGC circuit122 in accordance with the output of the exposure control circuit 124,and also controls the degree of opening of the iris 112 by means of thedriving circuit 136 a and the motor 136 b. The system control circuit138 adjusts the position of the focusing lens 110 a along the opticalaxis by means of the driving circuit 132 a and the motor 132 b inaccordance with the output of the focus control circuit 126, therebyplacing the photographic lens unit 110 into an in-focus state.

[0123] The white balance adjustment circuit 128 forms a control signalfor white balance adjustment, and the system control circuit 138controls the color processing circuit 130 in accordance with the outputof the white balance adjustment circuit 128. The color processingcircuit 130 generates a white-balanced luminance signal Y as well ascolor-difference signals R-Y and B-Y from the output of the AGC circuit122. A process circuit 140 converts into RGB signals the luminancesignal Y and the color-difference signals R-Y and B-Y outputted from thecolor processing circuit 130, and an encoder 142 generates a compositesignal from the output of the process circuit 140. The encoder 142 alsooutputs video signals in Y/C separation form.

[0124] The outputs of the color processing circuit 130 and the outputsof the process circuit 140 may of course be outputted to the outside ascomponent outputs.

[0125] A display generating circuit 144 generates display signalsindicative of operation mode, time and date and the like under thecontrol of the system control circuit 138, and an adder 146 adds theoutput of the display generating circuit 144 to the composite output ofthe encoder 142 and applies a signal indicative of the addition resultto an electronic viewfinder 148. Thus, a photographer can view variouskinds of information together with a subject to be photographed, on thescreen of the electronic viewfinder 148. Further, since a compositesignal is inputted to the electronic viewfinder 148 from a reproducingsystem which will be described later, it is possible to view areproduced image.

[0126] The photographer also can set photographic conditions, such asphotographic mode, photographic magnification and exposure, by operatingan operation key 150.

[0127] If photographic image information is digitally processed in thecamera shown in FIG. 12, each output signal may of course be outputtedin digital form. If analog outputs are needed, a D/A converter and aband-limiting low-pass filter may be provided at suitable locations.

[0128] The compression processing performed in the compression circuit66 shown in FIG. 6 will be described below in brief. Compression of animage is to reduce the amount of data by removing the redundancy of theimage. Compression of a still image utilizes the spatial redundancy ofthe image. Compression of a moving image utilizes its temporalredundancy in addition to its spatial redundancy, but the basicprinciples are based on still image compression techniques.

[0129] The element techniques of moving-image compression which conformsto, for example, the MPEG (Moving Picture Expert Group) standard, areDCT (discrete cosine transform) processing, quantization processing,coding processing and motion adaptation processing. Expansion can beregarded as the inverse process of compression. The DCT (discrete cosinetransform) processing, the quantization processing and the codingprocessing are common to both the moving-image compression andstill-image compression. These techniques will be described below inbrief in that order.

[0130] DCT converts spatial coordinates into frequencies. As thepre-processing of compression, an input picture is blocked into a pixelgroup of approximately 8×8 pixels. Multiplication processing using DCTcoefficients is performed in units of blocks, whereby space data areconverted into frequency data. Although the amount of data is notreduced by DCT alone, it is possible to concentrate data which is widelydispersed in the picture. In other words, an image has a generaltendency for more energy to concentrate on a lower spatial frequencyside, and DCT performs the function of increasing a compression ratiofor substantial compression processing to be executed at the succeedingstages.

[0131] The quantization processing rounds off the word lengths ofcoefficients which have been converted into frequencies by the DCTprocessing, thereby reducing the amount of data. For example, a datacoefficient indicative of each frequency component produced by DCT isdivided by an appropriate value, and the figures below the decimal pointof the resultant value are omitted. By omitting the figures below thedecimal point, it is possible to reduce the number of bits which arerequired to represent each coefficient data, whereby the total amount ofdata can be reduced. By setting a divisor for each frequency component,it is possible to increase the compression ratio while retaining therequired image quality.

[0132] The coding processing assigns to each data a length codecorresponding to the occurrence frequency of the data. First, a zigzagscan of the quantized data is performed to convert a two-dimensionaldata array into a unidimensional data string. The two-dimensional dataarray is scanned in a zigzag manner from a DC component towardhorizontal and vertical higher-frequency components, whereby the data isrearranged. By run length coding, the same numbers (mainly, zeros) whichcontinuously occur are replaced with one code which collectivelyrepresents such continuous occurrence. If the data which appear after aparticular location are all zeros, an end code is assigned to the data.This code indicates that if it is detected in a block, the transfer ofdata from the block is brought to an end, and realizes a great, datareduction effect.

[0133] By assigning codes of fewer bits to numbers having higheroccurrence frequencies, the substantial total number of coding bits canbe reduced.

[0134] The motion adaptation processing adds the technique of detectingand predicting a motion to still-image compression. The elementtechniques includes motion detection, motion predictive compensation andinterlacing coding. The motion adaptation processing will be describedbelow with illustrative reference to the case of compression of a movingimage conforming to a television broadcasting standard.

[0135] In the motion detection, image data is delayed by a time whichcorresponds to an integer multiple of a field (or frame) period, as by aframe memory, and two field (frame) pictures are compared in a time-axisdirection, thereby detecting a motion. As well-known motion detectingmethods, there are a method of obtaining the amount of motion as theabsolute value of the difference in luminance data between pictures anda method of computing the travel of a two-dimensional coordinate pointhaving a highest correlation, thereby detecting a motion vector.

[0136] The motion predictive compensation predicts a motion of an imageby the detected motion vector and transmits only the difference betweena predicted image and an actual image as compensation data. Accordingly,it is possible to reduce the amount of information to be transferred.Specifically, it is possible to reduce prediction errors in the case ofimages, such as an image which contains a large still-image portion andmoves to a small extent, an image which moves moderately and an imagewhich is rectilinearly travelling. Accordingly, a high compressioneffect can be achieved.

[0137] The interlacing coding forms a pixel block for compressionprocessing in units of fields. A television signal, such as an NTSCtelevision signal, has an interlaced structure in which the scanninglines of odd and even fields are alternately disposed. An odd field madeup of 262.5 odd lines and an even field made up of 262.5 even lines arepaired to form a frame picture made up of 525 lines.

[0138] If an odd field and an even field are simply combined when theamount of motion of a subject in a picture is large, a frame image blursand is visually extremely impaired. In a blurred portion of the picture,a vertical spatial correlation is lowered, so that no high compressionratio can be achieved by compression coding processing. If the amount ofmotion is small, this problems does not occur.

[0139] For this reason, if the amount of motion is small, a pixel blockfor compression processing is formed within a frame picture, while ifthe amount of motion is greater than a predetermined amount, a pixelblock for compression processing is formed within a field picture.

[0140]FIG. 13 is a schematic block diagram showing the arrangement of animage compressing circuit which adopts the above-described moving imagecompression processing techniques. Referring to FIG. 13, an SD or HDsignal outputted from the image pickup mode selecting circuit 64 shownin FIG. 6 is inputted through an input terminal 200. The video signalinputted through the input terminal 200 is inputted to an input buffer202 and a motion detecting circuit 204. The input buffer 202 functionsas 1-frame-period delay means, and its output is applied to a blockingcircuit 206 and the motion detecting circuit 204.

[0141] The motion detecting circuit 204 performs the above-describedcomparison computation on the video signal supplied from the inputterminal 200 and the video signal outputted from the input buffer 202,thereby detecting a motion vector. The motion detecting circuit 204outputs information indicative of the amount and direction of the motionto a system control circuit 220. On the basis of the motion vectorinformation, the system control circuit 220 determines whethercompression processing is to be performed in units of fields or in unitsof frames, and applies the resultant field/frame selection informationto the blocking circuit 206.

[0142] The blocking circuit 206 blocks the output image of the inputbuffer 202 into 8 pixels×8 pixels as shown in FIG. 14, in the units offields or frames according to the field/frame selection signal suppliedfrom the system control circuit 220. FIG. 15 shows the pixelarrangements of odd and even fields within one frame.

[0143] A DCT circuit 208 performs discrete cosine transform of theblocked pixel data supplied from the blocking circuit 206. By thisdiscrete cosine transform, the image data is converted into coefficientdata which is represented as a block of 8 pixels×8 pixels in a frequencyspace as shown in FIG. 16. As the general nature of an image, a DCcoefficient and lower-frequency AC components have larger values, whilehigher-frequency AC components have values close to zero.

[0144] The output of the DCT circuit 208 is applied to a quantizingcircuit 210 and a coefficient setting circuit 212. The coefficientsetting circuit 212 sets a quantizing coefficient for the quantizingcircuit 210 in accordance with a control signal supplied from the systemcontrol circuit 220 and the output of the DCT circuit 208. Thequantizing circuit 210 quantizes the output of the DCT circuit 208 withthe quantizing coefficient set by the coefficient setting circuit 212.Specifically, data coefficients for the individual frequency componentsare divided by adequate divisors, and the figures below the decimalpoints of the respective results are omitted to reduce the number ofbits. Incidentally, the divisors may differ among the individualfrequency components.

[0145] A coding circuit 214 first performs a zigzag scan of the outputof the quantizing circuit 210 in the zigzag manner shown in FIG. 17 froma DC component toward horizontal and vertical higher-frequencycomponents as shown in FIG. 17, thereby unidimensionally rearranging thedata. After then, the coding circuit 214 replaces continuing zeros witha predetermined code indicative of the number of the continuing zeros byrun length coding. As described previously, if all the data which appearafter a particular location are zeros, the coding circuit 214 assigns anend code to the data. The coding circuit 214 also assigns a short codeto data the occurrence frequency of which is high, by variable lengthcoding. Thus, the amount of data can be greatly reduced.

[0146] An amount-of-data calculating circuit 218 calculates the amountof the coded data generated by the coding circuit 214 and supplies theresult to the system control circuit 220. The system control circuit 220causes the coefficient setting circuit 212 to generate a quantizingcoefficient which is selected so that the amount of coded data to begenerated by the coding circuit 214 becomes a predetermined value.

[0147] The output of the coding circuit 214 is supplied to an outputbuffer 216. The output buffer 216 supplies the output of the codingcircuit 214 to a rear-stage circuit at a data rate. The output buffer216 also supplies information indicative of its internal data occupationratio to the system control circuit 220. The system control circuit 220controls the coefficient setting circuit 212 so that this occupationratio becomes stable in the neighborhood of a predetermined value inorder to prevent an overflow or a data shortage from occurring in theoutput buffer 216. Specifically, if the data occupation ratio is high,the system control circuit 220 causes the coefficient setting circuit212 to set a large coefficient (divisor), whereas if the data occupationratio is low, the system control circuit 220 causes the coefficientsetting circuit 212 to set a small coefficient (divisor).

[0148] In the arrangement shown in FIG. 13, the system control circuit220 controls the coefficient setting circuit 212 in accordance with theamount of coded data generated by the coding circuit 214 (the output ofthe amount-of-data calculating circuit 218) and the data occupationratio of the output buffer 216. An operator can instruct, through a modeselecting member 222, the system control circuit 220 to performswitching among the compression ratios (target values), the compressionsystems and the like. Of course, the system control circuit 220 canadaptively control the compression ratios (target values), thecompression systems and the like in accordance with the result of thedetection of a motion of an image and an operation mode set by the modeselecting member 222, whereby it is possible to efficiently compress amoving image. As a matter of course, by changing the coefficient to beset by the coefficient setting circuit 212, it is also possible to varythe compression ratio.

[0149] The recording system for recording a signal supplied from thecamera system of FIG. 12 will be described below in detail. FIG. 18 is adetailed block diagram showing the arrangement of the recording system.In the shown arrangement, a system control circuit 336 is substantiallyidentical to the system control circuit 138 of the camera system.

[0150] An A/D converter 300 converts the luminance signal Y into adigital signal, while an A/D converter 302 converts the chrominancesignal C into a digital signal. The luminance signal Y and thechrominance signal C are those supplied from the camera system describedpreviously with reference to FIG. 12. Of course, if digital processingis already performed in the camera system, neither of the A/D converters300 and 302 is needed.

[0151] A multiplexer 306 of a video data processing circuit 304multiplexes the outputs of the A/D converters 300 and 302 and outputsthe multiplexed data to an amount-of-information compressing circuit308. The amount-of-information compressing circuit 308 compresses themultiplexed data by using a compression system and a compression ratioaccording to mode information supplied from the system control circuit336. The amount-of-information compressing circuit 308 is substantiallyidentical to the circuit described above with reference to FIG. 13. Ofcourse, it is also possible to adopt a circuit arrangement forindividually compressing the amounts of information of luminance dataand chrominance data without multiplexing these data in the multiplexer306.

[0152] A shuffling circuit 310 rearranges the output data string of theamount-of-information compressing circuit 308 in accordance withappropriate rules, thereby preventing a transmission error from easilyoccurring in the data string. This shuffling operation also has theeffect of making uniform the uneven distribution of the amount ofinformation in a picture which is based on the presence of dense andsparse portions in the picture. The execution of the shuffling operationat a stage preceding the compression of the amount of information isconvenient for variable length coding, such as run length coding.

[0153] An ID adding circuit 312 adds identification (ID) information forrestoring the data shuffled by the shuffling circuit 310. Thisidentification information also contains mode information indicative ofmodes used for recording (the kind of compression system and the like),and is used as auxiliary information for expansion processing duringreproduction. An ECC adding circuit 314 adds an error-correcting code tothe output data of the ID adding circuit 312.

[0154] The video data subjected to the above-described processing in thevideo data processing circuit 304 is distributed into two channels by adata distributing circuit 316.

[0155] An A/D converter318 converts the L-channel signal of astereophonic audio signal into a digital signal, while an A/D converter320 converts the R-channel signal into a digital signal. A multiplexer324 of an audio data processing circuit 322 multiplexes the outputs ofthe A/D converters 318 and 320 and outputs the multiplexed data to anamount-of-information compressing circuit 326. The amount-of-informationcompressing circuit 326 compresses the multiplexed data by using acompression system and a compression ratio according to mode informationsupplied from the system control circuit 336.

[0156] If the recording rate of video data is large, as in the case ofan HD signal, audio information may also be recorded on a recordingmedium without compression.

[0157] A shuffling circuit 328 rearranges the output data string of theamount-of-information compressing circuit 326 in accordance withappropriate rules, thereby preventing a transmission error from easilyoccurring in the data string. An ID adding circuit 330 addsidentification (ID) information for restoring the data shuffled by theshuffling circuit 328. This identification information also containsmode information indicative of modes used for recording (the kind ofcompression system and the like), and is used as auxiliary informationfor expansion processing during reproduction. An ECC adding circuit 332adds an error-correcting code to the output data of the ID addingcircuit 330.

[0158] The audio data subjected to the above-described processing in theaudio data processing circuit 322 is distributed into two channels by adata distributing circuit 334.

[0159] A pilot generating circuit 338 generates a pilot signal fortracking servo, and a sub-code generating circuit 340 generatesauxiliary data to be recorded simultaneously with the video and audiodata. Such auxiliary data contains, for example, an address code forsearching for a position on a magnetic tape and the indexes of a programto be recorded.

[0160] A multiplexer 342 multiplexes one of the channel outputs of eachof the data distributing circuits 316 and 334, the pilot signaloutputted from the pilot generating circuit 338, and the sub-code datagenerated by the sub-code generating circuit 340. A multiplexer 344multiplexes the other channel output of each of the data distributingcircuits 316 and 334, the pilot signal outputted from the pilotgenerating circuit 338, and the sub-code data generated by the sub-codegenerating circuit 340. In the case of time-base multiplexing, themultiplexing of the pilot signal may be performed in accordance with anarea division ATF system which is well known in the field of digitalaudio tape recorders.

[0161] Digital modulating circuits 346 and 348 digitally modulate therespective outputs of the multiplexers 342 and 344 by means of, forexample, 8-10 conversion and an NRZI method.

[0162] The recording system according to the present embodiment isprovided with two pairs of magnetic heads. A head switching circuit 350switches the output of the modulating circuit 346 between recordingamplifiers 354 and 356 in accordance with a control signal supplied froma servo circuit 378. A head switching circuit 352 switches the output ofthe modulating circuit 348 between recording amplifiers 358 and 360 inaccordance with a control signal supplied from the servo circuit 378.The outputs of the recording amplifiers 354, 356, 358 and 360 arerespectively applied to magnetic heads 364 a, 364 c, 364 b and 364 d ofa rotary drum 362, whereby they are recorded on a magnetic tape 366.FIG. 19 shows one example of the track pattern of the magnetic tape 366.Each of the tracks contains a pilot signal P, audio data A, sub-code Sand video data V. FIG. 20 shows the detailed data structure of thesub-code S.

[0163] The servo circuit 378 controls the rotation of the rotary drum362 and the running of the magnetic tape 366 as well as the headswitching operations of the head switching circuits 350 and 352.Specifically, a rotation detector (FG) 376 for detecting the rotation ofa capstan motor 374 for causing the magnetic tape 366 to run isconnected to the capstan motor 374, and the servo circuit 378 controls,according to the output of the rotation detector (FG) 376, the capstanmotor 374 to cause it to rotate at a predetermined rotational speed.

[0164] Also, a drum motor 368 rotates the rotary drum 362, a rotationdetector (FG) 370 detects the rotational speed of the drum motor 368,and a rotational phase detector (PG) 372 detects the rotational phase ofthe rotary drum 362. The servo circuit 378 drives, according to theoutputs of the rotation detector (FG) 370 and the rotational phasedetector (PG) 372, the drum motor 368 to cause the rotary drum 362 torotate at a predetermined rotational speed. The servo circuit 378 alsocontrols the head switching operations of the head switching circuits350 and 352 in accordance with the output of the rotational phasedetector (PG) 372.

[0165] The system control circuit 336 controls the entire recordingsystem in accordance with an instruction inputted through an operationpanel (not shown) and on the basis of the operating state of each part.

[0166] The functions of the system control circuit 336 and the servocircuit 378 are realized by one microcomputer chip.

[0167] The reproducing system will be described below in detail withreference to FIG. 21. In FIG. 21, identical reference numerals are usedto denote constituent elements identical to those shown in FIG. 18.Specifically, in a manner similar to the recording operation, the servocircuit 378 causes the magnetic tape 366 to run at a predetermined speedby means of the capstan motor 374 as well as causes the rotary drum 362to rotate at a predetermined rotational speed and in a predeterminedrotational phase by means of the capstan motor 374.

[0168] The outputs of the magnetic heads 364 a, 364 c, 364 b and 364 dare respectively amplified by reproducing amplifiers 380, 382, 384 and386, and the outputs of the reproducing amplifiers 380, 382 and 384, 386are respectively applied to head switching circuits 388 and 390. Inaccordance with control signals supplied from the servo circuit 378, thehead switching circuit 388 switches the outputs of the reproducingamplifiers 380 and 382 therebetween, while the head switching circuit390 switches the outputs of the reproducing amplifiers 384 and 386therebetween. Demodulating circuits 392 and 394 respectively digitallydemodulate the outputs of the head switching circuits 388 and 390 by aredundancy detecting method, such as a differential detecting method, anintegral detecting method or Viterbi decoding, and output two-levelsignals. Each of the outputs of the demodulating circuits 392 and 394 ismade of information which includes video information, audio information,a pilot signal and sub-code information in a time division multiplexedstate.

[0169] Signal distributing circuits 396 and 398 supply the respectiveoutputs of the demodulating circuits 392 and 394 to predeterminedcircuits: that is to say, the video information is supplied to a dataintegrating circuit 406, the audio information is supplied to a dataintegrating circuit 424, the pilot signals are supplied to a pilotdetecting circuit 400, and the sub-code information is supplied to asub-code detecting circuit 402.

[0170] The pilot detecting circuit 400 detects as an error signal thetime difference between the pilot signal and a timing reference signalcorresponding to an off-track amount relative to the right and lefttracks, and supplies the error signal to the servo circuit 378. Theservo circuit 378 adjusts a tape transporting speed in accordance withthe error signal. The error signal can also be used as auxiliaryinformation for identification of a recording mode.

[0171] A sub-code detecting circuit 402 decodes the content of thesub-code from each of the S outputs of the signal distributing circuits396 and 398, and supplies the result to a system control circuit 404.The system control circuit 404 controls each part in accordance with thecontent of the reproduced sub-code.

[0172] The data integrating circuit 406 integrates the video informationsupplied from the signal distributing circuits 396 and 398 via twolines, and outputs the integrated video information to a video datareproducing circuit 408.

[0173] In the video data reproducing circuit 408, an error correctingcircuit 410 corrects an error which has occurred during recording orreproduction. If the error cannot be corrected, the error correctingcircuit 410 performs correction of the error by using interpolation. AnID detecting circuit 412 detects the ID added by the ID adding circuit312 during recording, and supplies the ID to the system control circuit404. A de-shuffling circuit 414 restores the data string rearranged bythe shuffling circuit 310, and an amount-of-information expandingcircuit 416 expands the data compressed by the amount-of-informationcompressing circuit 308, in accordance with the mode informationsupplied from the system control circuit 404, thereby restoring theoriginal image data. A data separating circuit 418 separates theoriginal image data into luminance data and chrominance data andsupplies the respective data to D/A converters 420 and 422. The dataseparating circuit 418 also outputs the digital image data to theoutside.

[0174] The D/A converter 420 converts the luminance data into an analogsignal, while the D/A converter 422 converts the chrominance data intoan analog chrominance signal. The analog signals are both outputted tothe outside, and are also converted into a composite signal, which isinputted to the adder 146 of FIG. 12. An operator can view a reproducedimage in the electronic viewfinder 148.

[0175] The data integrating circuit 424 integrates the audio informationsupplied from the signal distributing circuits 396 and 398 via twolines, and outputs the integrated audio information to an audio datareproducing circuit 426.

[0176] In the audio data reproducing circuit 426, an error correctingcircuit 428 corrects an error which has occurred during recording orreproduction. If the error cannot be corrected, the error correctingcircuit 428 performs correction of the error by using interpolation. AnID detecting circuit 430 detects the ID added by the ID adding circuit330 during recording, and supplies the ID to the system control circuit404. A de-shuffling circuit 432 restores the data string rearranged bythe shuffling circuit 328, and an amount-of-information expandingcircuit 434 expands the data compressed by the amount-of-informationcompressing circuit 326, in accordance with the mode informationsupplied from the system control circuit 404, thereby restoring theoriginal audio data. A data separating circuit 436 separates theoriginal audio data into L-channel audio data and R-channel audio dataand supplies the respective data to D/A converters 438 and 440. The dataseparating circuit 436 can also output the digital audio data to theoutside.

[0177] The D/A converter 438 converts the L-channel audio data into ananalog signal, while the D/A converter 440 converts the R-channel audiodata into an analog signal. The analog signals are both outputted to theoutside.

[0178] As described previously, the present embodiment is provided withthe three modes: the HD mode, the SD-High mode and the SD-Low mode.Since recording track patterns differ among the three modes, modeidentification information is recorded in sub-code areas so thatreproduction from tracks can be correctly performed in the case of anyof the three modes. The recording track patterns and mode identificationmethods for the respective modes will be described below. FIG. 22 showsmagnetic tape running speeds, the number of tracks per field andcompression ratios for the respective modes.

[0179] The SD-Low mode serves as a long-time recording mode for the SDsignal. Out of the four magnetic heads Ha, Hb, Hc and Hd shown in FIG.23, only the magnetic heads Ha and Hb are used, and five tracks perfield are formed as shown in FIG. 24. FIG. 25 shows the timing of headswitching. Recording current is alternately applied to the magneticheads Ha and Hb each time a drum PG pulse goes high while a rotary drumis being rotated at 150 rps.

[0180] In the SD-High mode, out of the four magnetic heads Ha, Hb, Hcand Hd shown in FIG. 26, only the magnetic heads Ha and Hc are used, andten tracks per field are formed as shown in FIG. 27. FIG. 28 shows thetiming of head switching. While the rotary drum is being rotated at 150rps, the recording current is applied to the magnetic head Ha if thedrum PG pulse goes high and to the magnetic head Hc if the drum PG pulsegoes low.

[0181] In the HD mode, all the four magnetic heads Ha, Hb, Hc and Hdshown in FIG. 29 are used, and twenty tracks per field are formed asshown in FIG. 30. FIG. 31 shows the timing of head switching. While therotary drum is being rotated at 150 rps, the recording current isapplied to the magnetic heads Ha and Hb if the drum PG pulse goes highand to the magnetic heads Hc and Hd if the drum PG pulse goes low.

[0182]FIG. 32 shows a flowchart of mode identification which is executedduring reproduction. First, the current reproduction mode is confirmed(S1). In Step S2, the flow proceeds to any one of Steps S3, S4 and S5 inaccordance with the result of the confirmation which indicates any oneof the SD-Low mode, the SD-High mode and the HD mode. Any value of “5”,“10” and “20” is set in a variable N (S2, S4 or S5).

[0183] The mode used during recording is identified on the basis of thesub-code of a reproduced digital signal (S6 and S7), and the subsequentreproduction mode is determined. In Step S7, the flow proceeds to anyone of Steps S8, S9 and S10 in accordance with the determined mode whichis any one of the SD-Low mode, the SD-High mode and the HD mode. Anyvalue of “5”, “10” and “20” is set in a variable M which determines thenumber of tracks per field (S8, S9 or S10).

[0184] The variables N and M are compared (S11). If N<M, the runningspeed of the magnetic tape is increased (S12). If N=M, the running speedof the magnetic tape is kept (S13). If N>M, the running speed of themagnetic tape is increased (S14). In other words, the running speed ofthe magnetic tape is controlled to become equal to the tape speedspecified by a mode selected during recording.

[0185] After the completion of Step S12, S13 or S14, the flow returns toStep S1, and the above-described processing is repeated.

[0186] An embodiment of a video recording and reproducing apparatus inwhich the down converter shown in FIG. 7 and the up converter shown inFIG. 33 are used as broadcasting system converters will be describedbelow with reference to FIG. 34 as well.

[0187]FIG. 33 shows one example of an NTSC-HD system converter whichserves as the up converter. In the NTSC-HD system converter shown inFIG. 33, an NTSC signal is decoded through a motion adaptive type NTSCdecoder 570, and the aspect ratio of the decoded signal is convertedfrom 4:3 to 16:9 in an aspect ratio conversion part 571. Then, thenumber of scanning lines is converted from 525 to 1,125 in anumber-of-scanning-lines conversion part 572, and the field frequency isconverted from 59.94 Hz to 60 Hz in a field frequency conversion part573. Thus, the NTSC signal is converted into an HD signal to beoutputted.

[0188]FIG. 34 is a block diagram showing a video recording andreproducing apparatus according to another embodiment of the presentinvention. An operator can select recording or reproduction, HD mode orSD mode and the like on an operation panel 500. The followingdescription refers to four kinds of operations of the recording andreproducing system of the apparatus. The input signal of this embodimentis an HD signal.

[0189] (1) Recording in SD Mode (Long-Time Recording Mode)

[0190] “RECORDING” and “SD” are selected on the operation panel 500, anda system controller 501 connects the movable contact of a switch 506 toa contact {circle over (1)} or {circle over (2)} thereof. An HD inputsignal is down-converted into an SD (for example, NTSC) signal by a downconverter 503. The system controller 501 also controls a switch 502 toconnect the movable contact of the switch 502 to a contact {circle over(1)} thereof. Thus, the SD signal is recorded on a tape 510 through arecording system 509. During this time, an SD monitor 504 is used.

[0191] (2) Recording in HD Mode (High Definition Mode)

[0192] “RECORDING” and “HD” are selected on the operation panel 500, andthe system controller 501 connects the movable contact of the switch 502to a contact {circle over (2)} thereof. The HD input signal is directlyrecorded on the tape 510. During this time, either one of an HD monitor505 and the SD monitor 504 can be selected.

[0193] If the HD monitor 505 is to be used, the movable contact of theswitch 506 is connected to the contact {circle over (1)} or {circle over(2)} thereof so that the HD signal can be directly outputted to the HDmonitor 505.

[0194] If the SD monitor 504 is to be used, the movable contact of theswitch 506 is similarly connected to the contact {circle over (1)} or{circle over (2)} thereof, and the HD signal is down-converted into anSD signal by the down converter 503. By connecting the movable contactof the switch 507 to any one selected from the contacts {circle over(1)}, {circle over (2)} and {circle over (4)} thereof, the SD signal canbe outputted to the SD monitor 504.

[0195] By adopting the above-described arrangement, it is possible toprovide a camera-integrated type VTR of reduced size.

[0196] (3) Reproduction in SD Mode

[0197] “REPRODUCTION” and “SD” are selected on the operation panel 500,and the system controller 501 connects the movable contact of the switch507 to a contact {circle over (3)} thereof. An SD signal reproduced fromthe tape 510 by a reproducing system 511 is displayed on the SD monitor504 as a reproduced output image. If the SD signal is to be displayed onthe HD monitor 505, it is converted into an HD signal by an up converter508 and the movable contact of the switch 506 is connected to a contact{circle over (3)} thereof.

[0198] (4) Reproduction in HD Mode

[0199] “REPRODUCTION” and “HD” are selected on the operation panel 500,and the system controller 501 connects the movable contact of the switch506 to a contact {circle over (4)} thereof. A reproduced HD signal isdirectly displayed on the HD monitor 505 as a reproduced output image.If the HD signal is to be displayed on the SD monitor 504, the movablecontact of the switch 506 is similarly connected to the contact {circleover (4)} and the HD signal is converted into an SD signal by the downconverter 503. When the movable contact of the switch 507 is connectedto a contact {circle over (1)} thereof, the SD signal can be displayedon the SD monitor 504. The following table shows the manner ofconnection of the contacts {circle over (1)} to {circle over (4)} ofeach of the switches 502, 506 and 507 during each of the SD and HDmodes. Recording Reproduction SD {circle over (1)} {circle over (3)} HD{circle over (2)} {circle over (4)}

[0200] Although in the above-described embodiment the up converter 508is employed, a multi-scan monitor may also be used instead of the HDmonitor 505. In the case of the multi-scan monitor, the up converter 508can be omitted because if an SD (for example, NTSC) signal is inputted,the SD signal is scanned by using 525 scanning lines/frame. As theSD-Low mode, an SD signal having a horizontal resolution ofapproximately 230 lines which is a standard image quality in generaldomestic apparatus may also be applied to the multi-scan monitor.

[0201] As can be readily understood from the above description, inaccordance with the above-described embodiment, since a compression modesuitable for image compression processing to be executed in a recordingsystem is selected according to a photographic mode selected in a imagepickup system, a photographic image can be efficiently compressed by theimage compression processing, so that good image quality and a highcompression ratio can be achieved.

[0202] Further, in accordance with the above-described embodiment, inone camera-integrated type VTR, it is possible to achieve selectiveutilization of a plurality of camera modes conforming to a plurality ofbroadcasting systems. Also, the setting of a compression mode, such asthe selection of a compression ratio and a compression system for animage, and the setting of the required recording mode in a VTR can beautomatically controlled by a system controller in accordance with theselection of a camera mode. Accordingly, it is possible to realize acamera-integrated type VTR which can be utilized in a variety ofapplications by an easy operation without the need to perform acomplicated connection or operation.

[0203] Also, in accordance with the above-described embodiment, since asingle down converter is used to perform recording of a video signalinput and reproduction of a recorded video signal, it is possible toreduce the circuit scale of the apparatus, and it is also possible toselectively record or reproduce an HD signal and an SD signal. Also, itis possible to employ an SD monitor as an output monitor for an HDsignal input. Further, since the SD monitor can be used as a monitor, itis possible to realize a camera-integrated type VTR which is reduced insize compared to conventional camera-integrated type VTRs.

[0204] In the above-described embodiment, the HD mode, the SD-Low modeand the SD-High mode are prepared as the three recording modes. However,the kinds of modes are not limited to these modes, and it is alsopossible to use three modes such as HD, SD and ED modes.

[0205] The manner of mode identification during reproduction and thesequence of control to be executed for the mode identification will bedescribed below with reference to FIG. 35.

[0206] Step P1: The current reproduction running mode of a VTR isconfirmed.

[0207] Step P2: A variable N is set to N=10 or N=20 according to whichof the three modes is selected.

[0208] Step P3: A sub-code is detected from a reproduced digital signal,and the mode used during recording is identified on the basis of thesub-code of the reproduced digital signal, and the required reproductionmode is determined.

[0209] Step P4: The required number of tracks per unit time M and a datacompression ratio CR are respectively set to M=10 or 20 and CR=5 or 10in accordance with any one of the three modes which is indicated byreproduced ID data.

[0210] Step P5: The target value of capstan speed control is set inaccordance with the result of a comparison between the values of thevariables N and M.

[0211] The flow proceeds from Step P5 to any one of the succeeding threesteps.

[0212] If N>M, it is determined that the current speed is greater thanthe speed used during recording, and the current speed is decreased.

[0213] If N<M, it is determined that the current speed is smaller thanthe speed used during recording, and the current speed is increased.

[0214] If N=M, the current speed is kept.

[0215] Step P6: A data expansion ratio is set to 1/CR and decoding isexecuted.

[0216] The flow returns to Step P1 for confirming the current mode, andthe above-described routine is repeated.

[0217] To obtain a better understanding of the operation of the focusingcontrol circuit 61 shown in FIG. 6, the relationship between systemconversion (conversion between television systems) and TVAF (automaticfocusing using a video signal) will be described below with reference toFIGS. 36 and 37.

[0218] The amount of information carried by an HDTV signal isapproximately five times that of information carried by an existingbroadcasting (SD) system. Further, the HDTV signal contains morehigh-frequency spectrum components than the SD signal.

[0219]FIG. 36 shows the level variations of the amount of high-frequencycomponents contained in the respective signals conforming to the twobroadcasting systems with respect to the movement of the focus of animage pickup optical system between its closest-distance position andits infinity position. Both curves A and B reach the respective peaks atan in-focus point.

[0220] The curve A indicates the variation curve of the HDTV signal,while the curve B indicates the variation curve of the existing TVsignal. The relationship between the heights at the in-focus point ofthe respective curves A and B is A≧B.

[0221] The relationship between the widths of in-focus areas “a” and “b”in which to restart an AF operation is a≦b. A sharper curve provides asmaller in-focus area for which AF restarting computations must beexecuted more frequently. In consequence, the curve A can achieve abetter focusing characteristic in terms of focusing accuracy.

[0222] In other words, if HDTV video information which contains a largeramount of information is used, it is possible to achieve TVAF of higherperformance.

[0223] For this reason, in an image pickup system employing a downconverter, video information which is not yet processed by the downconverter is suitably used as information for the aforesaid TVAF.

[0224] Incidentally, as shown in FIG. 37, signal frequency componentsdiffer between the existing NTSC and PAL broadcasting systems as well.Accordingly, if optimum ones of the signal frequency components areselectively employed according to the kind of subject or photographicconditions (the illuminance of surroundings), it is possible to improvedetection accuracy.

[0225] As shown in the coordinate plane of FIG. 37 which is defined bythree kinds of frequency axes, if it is assumed that the horizontalfrequencies of the NTSC and PAL video signals are the same, the NTSCsystem provides a picture which is made up of 60 fields/second withrespect to the temporal frequency axis and 525 scanning lines withrespect to the vertical frequency axis. Accordingly, the video signalcomponents of the NTSC video signal are present in the frequency areadefined by 60/2 and 525/2.

[0226] The PAL system provides a picture which is made up of 50fields/second with respect to the temporal frequency axis and 625scanning lines with respect to the vertical frequency axis. Accordingly,the video signal components of the PAL video signal are present in thefrequency area defined by 50/2 and 625/2.

[0227] By selectively utilizing the different characteristics inaccordance with the kind of subject whose image is to be picked up andthe kind of photographic mode, it is possible to further improve theperformance of TVAF.

[0228] The improvement of the performance of TVAF leads to not only animprovement in the diameter of a circle of least confusion at a finalin-focus position but also an improvement in the stability of theprocess of finding an in-focus position (for example, an unstablebehavior such as hunting or fluctuation can be reduced).

[0229] As described above, a subject image is photoelectricallyconverted by the CCD built in the HDTV camera 60 and an HD signal havinga high degree of definition and a large amount of information isoutputted.

[0230] An embodiment in which a concept called “scalability” is appliedto the hierarchial structure of image information of a VTR to improvedata handling will be described below with reference to FIGS. 38 to 49.

[0231] A technique for performing coding or decoding and recording orreproduction of HD information in a structure in which an NTSC signal isincluded in the HD information will be described below with illustrativereference to a two-layer structure consisting of the HD information andthe NTSC information.

[0232] First, encoding of an NTSC signal is performed and the encodedsinal is transferred (or recorded).

[0233] Then, a non-transmitted or unrecorded information portion istransferred (or recorded).

[0234] An operation which is performed by recording means having thearrangement shown in FIG. 38 when an HD signal is inputted thereto willbe described below.

[0235] The input HD signal is down-converted into an SD signal by a downconverter 661, and the output of the down converter 661 is inputted toan SD-signal encoder 662. The encoded SD signal is divided into twochannels by a recording channel divider 663, and the two outputs of therecording channel divider 663 are supplied to recording head amplifiers671 and 673, respectively. Then, information recording tracks are formedon a magnetic recording medium 660 by magnetic recording heads 672 and674. In the meantime, the output of the SD-signal encoder 662 issupplied to an SD-signal decoder 665 and, in an up converter 664, theoutput of the SD-signal decoder 665 is converted into an HD signal whichcontains an image distortion (error) occurring during encoding/decoding.If this degradation signal (recording SD information) is subtracted fromthe previous input signal, a difference signal for forming an HD signalcan be obtained. Such a difference signal is formed by a subtractor 669,and the amount of data contained in the difference signal is reduced ina data compressor 666, and the output of the data compressor 666 isinputted into a data formatter 667 for causing the SD signal to conformto the recording standard of the HD signal. The output of the dataformatter 667 is divided into two channels by a recording channeldivider 668 similar to the aforesaid recording channel divider 663. Thethus-obtained HD additional information is supplied to recording headamplifiers 675 and 677. Magnetic recording heads 676 and 678sequentially record and form a pair of HD information recording tracksin an area adjacent to the pair of SD information recording tracksformed by the outputs of the divider 663 on the magnetic recordingmedium 660.

[0236] The manner of the above-described recording operation isdiagrammatically shown in FIG. 40.

[0237] The SD information and the HD additional information, which arein the inclusive relationship shown by a symbolic block (left)representative of the amount of image information, are respectivelyrecorded by two pairs of double azimuth (+/−) heads at the rate of twotracks at one time, and a total of four tracks constitute a basic unit.

[0238] The tape transporting speed used during the above-describedrecording operation is selected to be two times the tape transportingspeed used during SD recording (N=2).

[0239]FIG. 39 is a schematic view showing the operation of an SDrecording mode for recording only the SD information on a recordingmedium by one pair of double azimuth (+/−) heads at the rate of twotracks at one time.

[0240] The tape transporting speed used during this recording operationis selected to be a standard speed (N=1).

[0241] An example of the arrangement of reproducing means forreproducing arbitrary information from a magnetic tape on which SDinformation and HD additional information are recorded in theabove-described manner will be described below, and the reproducingoperation of the reproducing means will be described with reference toFIG. 41.

[0242] Signals, which are respectively outputted from a pair of magneticheads 702 and 704 for tracing only a pair of SD information recordingtracks on a magnetic tape 709 recorded in an HD recording mode, arerespectively amplified by head amplifiers 701 and 703. The signalsoutputted from the head amplifiers 701 and 703 are integrated by a datacombiner 693, and the output of the data combiner 693 is decoded fromits recording data format into an SD signal, such as an NTSC signal, byan SD-signal decoder 692. The SD signal is converted into an HD-signalformat by an up converter 691. The processing of this SD-HD formatconversion is the inverse of the processing performed by theabove-described down converter.

[0243] Signals, which are respectively outputted from a pair of magneticheads 706 and 708 for tracing only a pair of HD additional informationrecording tracks on the magnetic tape 709 recorded in the HD recordingmode, are respectively amplified by head amplifiers 705 and 707. Thesignals outputted from the head amplifiers 705 and 707 are integrated bya data combiner 697, and the output of the data combiner 697 is decodedfrom its recording data format into a compressed HD additional signal byan HD-signal decoder 696. The compressed HD additional signal isconverted into an HD additional signal by a data expander 695.

[0244] The SD information and the HD additional information which havebeen converted into a common HD signal format in the above-describedmanner are added together by an adder 694, whereby the original HDsignal is reconstructed.

[0245]FIG. 42 schematically shows the manner of the above-describedreproduction from the magnetic tape recorded in the HD recording mode.

[0246] Both the period during which a pair of magnetic heads for tracingonly a pair of HD additional information recording tracks on a magnetictape recorded in the HD recording mode trace the magnetic tape and theperiod during which a pair of magnetic heads for tracing a pair of SDinformation recording tracks on the magnetic tape trace the magnetictape are selected on the basis of the angle over which the magnetic tapeis wrapped around a head drum. If each of the periods is selected to be180 degrees, an HD additional data reproduction period and an SD datareproduction period appear alternately at intervals of one-half rotationof the head drum.

[0247] During each of the data reproduction periods, the signalsrecorded on two tracks are reproduced by either of the pairs of doubleazimuth heads provided on the rotary drum. The signals recorded on atotal of four tracks are reproduced as a basic unit.

[0248] Accordingly, the signals recorded on four tracks which constitutethe basic unit of the aforesaid information can be reproduced during onerotation of the head drum. The inclusive and combination relationshipsbetween the SD information and the HD additional information which arereproduced in the above-described manner are shown in the right-handpart of FIG. 42 by using symbolic blocks each representative of theamount of image information.

[0249] Compatible reproduction which is most important in the presentinvention will be described below.

[0250] The following description refers to a case where an SD recordingapparatus having no recording function for the HD recording mode is usedto perform reproduction from a magnetic tape recorded in the HDrecording mode, as shown in FIG. 49.

[0251]FIG. 44 shows the manner in which a pair of magnetic heads fortracing a pair of SD information recording tracks on a magnetic taperecorded in the SD recording mode traces the magnetic tape to reproducean SD signal. Only one pair of double azimuth heads are provided on ahead drum, and SD information alone is recorded on each track of themagnetic tape. In this case, each SD data reproduction period occursonly once during one rotation of the head drum. Since the tapetransporting speed is the standard speed (N=1), the SD informationrecorded on each recording track is sequentially reproduced withoutskipping any of the recording tracks. FIG. 44 schematically shows themanner of the above-described reproducing operation.

[0252] If recording-mode identification information, such as ID, isdetected from a video area or a sub-code area by the detector 771 shownin FIG. 49 during the SD recording mode reproducing operation, acompatible reproduction mode is selected. When a servo circuit 773receives an instruction from the detector 771, the servo circuit 773sets the current tape transporting speed to a double speed equal to thetape transporting speed for the HD reproduction mode. Incidentally, amotor 774 is provided for driving a capstan, and a frequency generator(FG) 775 is provided so that the servo circuit 773 can confirm the stateof rotation of the capstan.

[0253] The pair of double azimuth heads for SD signals, which areprovided on the head drum, trace only pairs of SD information recordingtracks on a magnetic tape recorded in the HD recording mode. However,since no magnetic heads for HD signals are provided, the magnetic tapeis transported without tracing a pair of HD additional informationtracks. Accordingly, an HD addition data track idle running period andan SD data reproduction period alternately appear at intervals ofone-half rotation of the head drum. FIG. 43 schematically shows themanner of the above-described reproducing operation.

[0254] Reproduction from only two tracks for SD signals out of fourtracks which constitute one basic unit is performed by the pair ofdouble azimuth (+/−) heads provided on the rotary drum, at intervals ofone rotation period.

[0255] The signal reproduced in the above-described manner is convertedinto an SD signal, such as an NTSC or PAL signal, by the SD-signaldecoder 772 shown in FIG. 49, and the SD signal is outputted from theSD-signal decoder 772. The manner of the above-described reproductionfrom the recorded tracks is shown in FIG. 45 in the form of a recordingtrack pattern.

[0256] The recording tracks shown in FIG. 45 constitute groups eachconsisting of four tracks indicated by characters “a” to “d” affixed tothe respective numbers.

[0257] The characters “a” and “b” indicate tracks for SD signals(represented by meshes), and the characters “c” and “d” indicateadditional tracks for HD signals.

[0258] In the compatible reproduction mode, reproduction from only thetracks “a” and “b” is performed, and no reproduction from the track “c”nor “d” is performed.

[0259]FIG. 46 is a graphic representation showing a head relative speedVhead determined by a tape transporting speed Vtape and a head drumrotational speed Vdrum, and the horizontal and vertical axes representthe tape transporting speed Vtape and the head drum rotational speedVdrum, respectively.

[0260] Since the head relative speed Vhead reaches 9,000 rotationsduring the SD mode, it is not practical to increase the rotational speedto a further extent for the purpose of coping with the HD mode. If therotational speed is selected to be not less than 9,000 rotations, twokinds of trace angles are formed in the case of the respective standardand double speeds, as shown in FIG. 46.

[0261] A line V1 indicates the case of reproduction of an SD moderecording, and a line V2 indicates the case of reproduction of an HDmode recording. In the case of the compatible reproduction modeaccording to the present embodiment, the tape transporting speed Vtapeand the drum rotation speed Vhead are completely the same as those usedin the HD reproduction mode, the head trace V2 is selected so that an SDtrack portion can be traced without any problem. Each of FIGS. 47 and 48is a table showing whether each of the SD and HD reproduction modes canbe used for magnetic tapes recorded in the respective SD and HDrecording modes, and FIG. 47 shows the case of an SD signal reproducingapparatus, while FIG. 48 shows the case of an HD signal reproducingapparatus.

[0262] As can be seen from FIGS. 47 and 48, not only the HD signalreproducing apparatus but also the SD signal reproducing apparatus caneffect reproduction from any of the magnetic tapes recorded in the SDrecording mode or the HD recording mode.

[0263] It is to be noted that since reproduction from a magnetic taperecorded in the SD recording mode can be performed in the HD-signalformat, “recording mode SD/reproduction mode HD” of FIG. 48 can also beregarded as “possible” although the image quality, such as resolution,is equivalent to SD quality.

[0264] In the present embodiment, although the concept of a hierarchicalcoding system has been described with illustrative reference topyramidal coding, the kind of coding system is not limited to thepyramidal coding. For example, another hierarchical coding technique,such as sub-band coding, can of course be used without departing fromthe scope and spirit of the present invention.

[0265] Incidentally, the head relative speed Vhead is not limited to9,000 rotations, and, for example, 4,500 rotations may be selected. Itis also possible to adopt an arrangement which switches the headrelative speed Vhead as well as the characteristics of its controlsystem on the basis of a decision as to whether the HD mode or the SDmode is selected.

[0266] According to the embodiment utilizing the above-describedscalability, it is possible to achieve a remarkable improvement in thecharacteristic of compatible reproduction from a recorded medium, whichcannot be attained by conventional image recording systems because oftheir different coding systems.

[0267] Also, it is possible to effect reproduction from a recordingmedium recorded in any recording mode, by means of not only higher-orderequipment but also lower-order equipment.

[0268] Furthermore, since a lower-order system needs only to have aservo mechanism for effecting switching between media driving speeds,users can easily introduce lower-order systems without making largeprior investments.

What is claimed is:
 1. An image processing apparatus comprising: imagepickup means having a plurality of photographic modes; compressionprocessing means for performing compression processing of an imagepickup signal outputted from said image pickup means, said compressionmeans having a plurality of compression modes; and selecting means forselecting one of the compression modes of said compression processingmeans in accordance with a selected one of the photographic modes ofsaid image pickup means.
 2. A video recording apparatus comprising:image pickup means capable of conforming to a plurality of televisionstandards; recording means for compressing data outputted from saidimage pickup means at a compression ratio according to a televisionstandard selected from the plurality of television standards andrecording on a recording medium compressed data and identificationinformation for identification of the selected television standard;setting means for setting the selected television standard; andcontrolling means for controlling said image pickup means and saidrecording means in accordance with a setting of said setting means.
 3. Avideo reproducing apparatus comprising: reproducing means forreproducing video data compressed according to a television standard andidentification information for identification of the television standardfrom a recording medium on which the video data and the identificationinformation are recorded, and performing expansion processing of thevideo data; and controlling means for controlling said reproducing meanson the basis of the identification information reproduced from therecording medium.
 4. A video recording and reproducing apparatuscomprising: a system converter for converting a first video signalconforming to a first television standard into a second video signalconforming to a second television standard; recording means forrecording the first or second video signal on a recording medium;switching means for supplying to said recording means the first videosignal or the second video signal obtained from said system converter;reproducing means for reproducing the first or second video signal fromthe recording medium; and signal supplying means for supplying the firstvideo signal reproduced by said reproducing means to said systemconverter.
 5. A video system comprising: recording means for recordingvideo information, which is hierarchically coded, while forming a datarecording area on a recording medium in accordance with a hierarchicalstructure of the video information and at least one recording mode of aplurality of recording modes each having a different recordingprocessing; and reproducing means capable of setting a reproduction modeaccording to the at least one recording mode and the hierarchicalstructure.
 6. A video system comprising: recording means for recordingvideo information, which is hierarchically coded, while forming a datarecording area on a recording medium in accordance with a hierarchicalstructure of the video information and at least one recording mode of aplurality of recording modes each having a different recordingprocessing; and reproducing means capable of setting a reproduction modewithin a range of the hierarchical structure irrespective of the atleast one recording mode.